激光选区熔化成形TiB_2增强S136模具钢  

Selective Laser Melting of TiB_2-Reinforced S136 Die Steels

作　　者：胡辉 周燕[1,2] 文世峰 魏青松[1] Hu Hui;Zhou Yan;Wen Shifeng;Wei Qingsong(State Key Laboratory of Material Processing and Die & Mould Technology,Huazhong University of Sczence and Technology,Wuhan,Hubei 430074,China;Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China)

机构地区：[1]华中科技大学材料成形与模具技术国家重点实验室,湖北武汉430074 [2]中国地质大学(武汉)工程学院,湖北武汉430074

出　　处：《中国激光》2018年第12期125-134,共10页Chinese Journal of Lasers

基　　金：国家863计划(2015AA042501)

摘　　要：利用激光选区熔化(SLM)工艺成形TiB2/S136复合材料,研究了激光体能量密度η对SLM成形试样致密度、微观组织及力学性能的影响。采用X射线衍射仪、场发射扫描电镜、透射电镜等研究成形试样物相成分、表面形貌及微观组织。结果表明:当η过低时,粉末熔化不完全,形成大量残余孔隙;而当η过高时,受热应力影响,成形试样存在微裂纹。当η=66.7J/mm3时,成形试样表面缺陷少,致密度高达97.3%,存在细化的、分布均匀的等轴晶,其平均显微硬度高达742.4HV0.1,平均摩擦系数和磨损率分别为0.5593和0.272×10-4 mm3·N-1·m-1,耐磨性能优异,抗拉强度达到1051.3 MPa,延伸率为5.84%,塑性较好。因此,SLM成形TiB2/S136复合材料的最佳η为66.7J/mm3,η过高或过低,均会严重影响TiB2/S136复合材料的致密度及力学性能,该研究为SLM成形高性能模具钢材料提供了有益的理论和工艺借鉴。The selective laser melting (SLM) technology is used to process the TiB2/S136 composites and the effect of laser energy density η on the densities, microstructures and mechanical properties of SLM-processed specimens is investigated. X-ray diffraction instrument, field emission scanning electron microscopy and transmission electron microscopy are used to study the phase compositions, surface morphologies and microstructures of specimens. The results show that, when η is low, the powders are not fully molten and thus a large amount of residual pores are formed. However, when η is too high, the micro-cracks are formed in the specimens because of thermal stress. When η is 66.7 J/mm3, the specimens have less surface defects, their densities are up to 97.3%, and there exist fine and uniformly-distributed equiaxed grains. As for these specimens, the average micro-hardness is up to 742.4 HV0.1, and the average friction coefficient and wear rate are 0.5593 and 0.272×10-4 mm3·N-1·m-1, respectively, indicating an excellent abrasion resistance performance. The tensile strength is 1051.3 MPa and the elongation is 5.84%, indicating a relatively good plasticity. Above all, the optimal η for the SLM-processed TiB2/S136 composites is 66.7 J/mm3, and if η is too high or too low, the densities and mechanical properties of TiB2/S136 composites would be seriously affected. This study provides a useful theoretical basis and a process guidance for SLM-processed high-performance die steels.

关 键 词：激光光学 激光选区熔化 能量密度 TiB2/S136复合材料 微观组织 机械性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程]